Isuzu KB P190. Manual - part 461

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-227

3

1.

Turn OFF the ignition.

2.

Wait 1 minute for the fuel pressure to bleed
down from the fuel rail.

3.

Turn ON the ignition, with the engine OFF. DO
NOT start the engine.

4.

Observe the Fuel Rail Pressure (FRP) Sensor
parameter with the scan tool.

Does the scan tool indicate within the specified
value?

0.9 to 1.0 volt

Go to Step 4

Go to Step 10

4

1.

Turn OFF the ignition.

2.

Place the transmission in Neutral and set the
parking brake.

3.

Start the engine.

4.

Accelerate the engine between idle and
W.O.T. (accelerator pedal full travel) many
times.

5.

Let idle for at least 3 minutes while observing
the DTC Information with a scan tool.

Is DTC P1094 set?

—

Go to Step 14

Go to Step 5

5

1.

Start the engine.

2.

Perform the Cylinder Balance Test with a scan
tool.

3.

Command each injector OFF and verify an
engine speed change for each injector.

Is there an injector that does not change engine
speed when commanded OFF?

—

Go to Step 12

Go to Step 6

6

1.

Check the fuel system line connections
between the fuel tank and the fuel supply
pump for tightness and all fuel hoses for cuts,
cracks and for the use of proper clamps.

Notice: Air in the fuel system will cause fuel rail
pressure fluctuations especially at high engine
speed and load, which may set this DTC.

2.

Start the engine and check for high side fuel
system leaks at the fuel supply pump and fuel
rail.

Notice: Fuel may leak under the cylinder head
cover from the inlet high pressure line. In such
case, the engine oil level will rise. Inspect for fuel
leakage into the engine oil.

3.

Repair any fuel system leaks as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 7

Step

Action

Value(s)

Yes

No

6E-228   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

7

Notice: Make sure the in-tank fuel pump operation
before performing the following procedures. Refer
to In-tank Fuel Pump System Check in this section.

1.

Turn OFF the ignition.

2.

Disconnect the fuel hose from the fuel supply
pump suction side. In order to measure the
discharged fuel amount, put the hose into a
bottle or a container with a scale. (The inlet of
a bottle or a container must be larger than the
diameter of hose.)

3.

Turn ON the ignition for 20 seconds, with the
engine OFF.

4.

Turn OFF the ignition for 10 seconds.

5.

Perform 3 and 4 three times. The accumulated
fuel of three ignition cycles must be more than
300 cc. (Normal amount is more than 100 cc
per one ignition cycle.)

Notice: If there is a leak or a restriction on the
suction side, the fuel from the hose will not flow out
sufficiently that is most likely caused by fuel
leakage, clogged fuel filter, kinked or crushed fuel
hose or pipe. Also inside the fuel tank for any
foreign materials may be getting drawn into the fuel
line pickup.

6.

Repair fuel system leaking or restrictions as
necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 8

8

1.

Remove the fuel hose that connects to the fuel
supply pump suction side and substitute a
clear hose.

Notice: The hose must be cleaned before
connecting to the fuel line. Otherwise, foreign
material internal to the hose may damage the fuel
supply pump.

2.

Bleed the fuel system. Repeat as necessary
until the engine starts.

3.

Let the engine run at idle for at least 1 minute.

4.

Observe the clear hose while holding the
engine speed higher than 3000 RPM for a
minimum of 1 minute.

Notice: If many air bubbles appear in the fuel,
check the fuel line connections between the fuel
supply pump and the fuel tank for tightness and all
fuel hoses for cuts, cranks and for the uses of
proper clamps.

5.

Repair or replace as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 9

Step

Action

Value(s)

Yes

No

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-229

9

1.

Turn OFF the ignition.

2.

Disconnect the FRP regulator harness
connector.

3.

Inspect for an intermittent, for poor
connections and corrosion at the harness
connector of the FRP regulator (pins 1 and 2
of E-50).

4.

Disconnect the ECM harness connector.

5.

Inspect for an intermittent, for poor
connections and corrosion at the harness
connector of the ECM (pins 34, 50, 54 and 70
of E-90).

6.

Test for high resistance on each circuit.

7.

Repair the connection(s) or circuit(s) as
necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 13

10

1.

Turn OFF the ignition.

2.

Disconnect the FRP sensor harness
connector.

3.

Inspect for an intermittent, for poor
connections and corrosion at the harness
connector of the FRP sensor (pins 1, 2 and 3
of E-48).

4.

Disconnect the ECM harness connector.

5.

Inspect for an intermittent, for poor
connections and corrosion on at the harness
connector of the ECM (pins 47, 48, 68 and 69
of E-90).

6.

Test for high resistance on each circuit.

7.

Repair the connection(s) or circuit(s) as
necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 11

11

Replace the FRP sensor. Refer to FRP sensor
Replacement.

Did you complete the replacement?

—

Go to Step 15

—

12

Important: Replacement fuel injector must be
programmed.
Replace the appropriate fuel injector that does not
change engine speed when commanded OFF.
Refer to Fuel Injector Replacement/ Fuel Injector
ID Code Data Programming.

Did you complete the replacement?

—

Go to Step 15

—

13

Important: The fuel supply pump must be timed to
the engine and adjustment value must be learned
to the ECM.
Notice:  Always replace the fuel filter cartridge
when a fuel supply pump is replaced.
Replace the fuel supply pump and fuel filter
cartridge. Refer to Fuel Supply Pump Replacement
and Fuel Filter Cartridge Replacement.

Did you complete the replacement?

—

Go to Step 15

—

Step

Action

Value(s)

Yes

No

6E-230   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

14

Notice: There is a possibility that the pressure
limiter valve stuck open or opening pressure has
fallen.
Replace the pressure limiter valve. Refer to Fuel
Rail Replacement.

Did you complete the replacement?

—

Go to Step 15

—

15

1.

Reconnect all previously disconnected
harness connector(s).

2.

Clear the DTCs with a scan tool.

3.

Turn OFF the ignition for 30 seconds.

4.

Start the engine.

5.

Operate the vehicle within the Conditions for
Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/ Failure
Records.

Did the DTC fail this ignition?

—

Go to Step 2

Go to Step 16

16

Observe the DTC Information with a scan tool.

Are there any DTCs that you have not diagnosed?

—

Go to DTC List

System OK

Step

Action

Value(s)

Yes

No